1. Field
The present disclosure relates to a thread winder which winds a thread supplied from a thread spool onto a bobbin attached to a thread winding shaft, and a sewing machine provided with the thread winder.
2. Related Art
A thread winder is generally provided in an arm of a sewing machine to wind a thread supplied from a thread spool, onto an emptied bobbin. A conventional thread winder 1 includes a base 2 mounted on an upper wall of an arm constituting a sewing machine and a thread winding shaft 3 protruding through the base 2 upward as partially shown in FIG. 12. A bobbin 5 is detachably attached to a bobbin holder 4 so as to be placed on the holder. The bobbin 5 includes a cylindrical bobbin shaft 5a with upper and lower ends and disc-like flanges 5b formed on the upper and lower ends of the bobbin shaft 5a respectively.
The thread winding shaft 3 is laterally movable between a preparation position and a winding position although not shown in detail. When the thread winding shaft 3 assumes the winding position, a rubber ring provided on the lower end of the thread winding shaft 3 is pressed against a side surface of a pulley driven by a sewing machine motor thereby to be brought into contact with the latter. As a result, a torque developed by the pulley is transmitted to the thread winding shaft 3 so that the thread winding shaft 3 is rotated, whereby a tread T drawn from the thread spool is wound on the bobbin shaft 5a of the bobbin 5.
In execution of a thread winding work, a user firstly attach an empty bobbin 5 to the thread winding shaft 3 assuming the preparation position. The thread T drawn from the thread spool is then passed through a predetermined threading passage, and a distal end of the thread T (a winding start portion) is wound by a small amount on the bobbin shaft 5a. Subsequently, the thread winding shaft 3 is moved to the winding position, whereupon a torque is obtainable from the pulley. When the user operates a start/stop switch in this state, a sewing machine motor is driven so that the thread winding shaft 3 is rotated via the pulley, whereby the thread T is wound on the bobbin 5.
When the user carries out the above-described thread winding preparatory work with the aforementioned thread winder, the thread T which should be wound on the bobbin shaft 5a sometimes detach downward from the lower flange 5b of the bobbin 5. In this case, the thread T detached downward gets into a gap between the flange 5 and the bobbin holder 4, twining around the thread winding shaft 3.
To overcome the above-described problem, a ring-shaped convex portion 6 is provided so as to surround the bobbin holder 4 so that the thread T is prevented from downwardly detaching from the flange 5b. In this construction, however, the level of an upper end of the convex portion 6 corresponds with the level of the lower end side flange 5b of the bobbin 5 so as not to detach from the flange 5b. The level of the upper end of the convex portion 6 cannot exceed the level of the lower end side flange 5b. As a result, when the user winds the distal end of the thread T on the bobbin 5 in the preparatory work for thread winding, there is still a possibility that the thread T may get into a space at the side of the underside of the flange 5b or the gap between the flange 5 and the bobbin holder 4. Accordingly, the effect of preventing the thread T from twining around the thread winding shaft 3 is insufficient.